Lee Deokgu (이덕구) was born in 1920 (the exact month and day are unknown) in Sinchon, Jocheon, Jeju Island (제주도 조천읍 신촌리). The youngest of three brothers, Lee Deokgu went to Japan to study from when he was relatively young. Towards the end of World War II he was drafted into the Japanese army during his final year of university, and he would return to Jeju following the country's liberation from Japan.

Upon returning to Jeju he would become a teacher at Jocheon Middle School (조천중학교) where he taught history and geography. He is remembered as a teacher who was very passionate and fun. He is also remembered for having a very strong nationalistic streak in him.

So, when the April 3 Incident started he headed to Halla Mountain (한라산) and became the leader of the Jocheon armed resistance unit (조천면 유격대 대장). He would later become the overall commander of the armed resistance when Kim Dalsam (김달삼) departed for North Korea to take part as a South Korean representative at the People's Convention in Haeju.

Lee Deokgu oversaw a very difficult period for the resistance in Jeju. Shortly after he became commander, the new Republic of Korea (AKA South Korea) government was officially formed with Syngman Rhee (이승만) as president. Syngman Rhee wanted to ensure that everyone recognized the new government's authenticity and authority and he saw the fighting in Jeju as a potential threat to that. So, he immediately began to order extremely harsh and brutal methods to suppress the fighting.

Lee Deokgu was killed by the police (although some reports say that he ultimately committed suicide rather then by killed by the police) on June 7, 1949 at Sanjeon (산전). The police brought Lee Deokgu's body back to the police station in Jeju City. There they crucified it in front of the station to serve as a warning and message for other resistance members and the general public. The body was only displayed for a day as it was the rainy season at the time and it quickly began to decay and smell. So, the police took his body down and burned it in the forest.

While the armed resistance was already beginning to come apart due to the relentless and merciless tactics employed by the government suppression forces, Lee Deokgu's death essentially brought the end of the resistance.